That's interesting. I suppose that, since the DE's are released periodically as "vintages", they feel no particular need to standardize the color. Do you suppose that each vintage is a single vatting? I'd have to guess so.

I would agree that the DEs are vattings of one special year and therefore a vintage. It would not make much sense to give a year and have a vatting of different distillation periods. If it were so what would the statement of a certain year mean? As to the colour I woul think that the PX Sherry gives enough colour and that there is no need for "Einheitliche Farbgebung", homogenisation of colours between the editions.

Well, just devil's advocating here, but you could certainly have more than one vatting in any given year. I doubt that's the case, though. And the possible use of coloring wouldn't be because there isn't sufficient color in the whisky, but to standardize it. Again, apparently not the case.